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新型コロナウイルスの感染力

タイのブログ-タイ情報とコラム

新型コロナウイルスの安定性
を調べた記事を読みました。

Stability of SARS-CoV-2 in different environmental conditions

僕の理解した限りでは、

新型コロナウイルス、

このウイルスは高温に弱い。
70℃、5分間で不活化する。
煮沸消毒が有効なようです。

温度により生存力が異なり、
4℃で14日目も感染力あり。
22℃で7日以降は検出なし。
37℃で2日以降は検出なし。
(PDFのデータ)

季節(気温)の影響あっても、
真夏の気温でも感染力あり。
低温では感染力が長く残る。

新型コロナウイルス、

滑らかな表面で安定する。
(室温22℃湿度65%で)
木や布で1日後にも検出。
ガラス・紙幣で2日後も。
金属・プラスチックで4日。
マスクの外側で7日後も。
(PDFのデータ)

接触感染に注意が必要。
マスクは頻繁に洗浄消毒。

一般的な洗浄消毒方法で、
ウイルスは不活化します。

とくに外出したら、
物を触る前には手を消毒、
触った後には手洗いです!

We previously reported the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in different clinical samples.
This virus can be detected on different surfaces in a contaminated site.
Here, we report the stability of SARS-CoV-2 in different environmental conditions.

We first measured the stability of SARS-CoV-2 at different temperatures. SARS-CoV-2 in virus transport medium (final concentration ∼6·8 log unit of 50% tissue culture infectious dose [TCID50] per mL) was incubated for up to 14 days and then tested for its infectivity.

The virus is highly stable at 4°C, but sensitive to heat. At 4°C, there was only around a 0·7 log-unit reduction of infectious titre on day 14. With the incubation temperature increased to 70°C, the time for virus inactivation was reduced to 5 mins.

We further investigated the stability of this virus on different surfaces. Briefly, a 5 μL droplet of virus culture (∼7·8 log unit of TCID50 per mL) was pipetted on a surface (∼cm2 per piece) and left at room temperature (22°C) with a relative humidity of around 65%. The inoculated objects retrieved at desired time-points were immediately soaked with 200 μL of virus transport medium for 30 mins to elute the virus. Therefore, this recovery of virus does not necessarily reflect the potential to pick up the virus from casual contact.

No infectious virus could be recovered from printing and tissue papers after a 3-hour incubation, whereas no infectious virus could be detected from treated wood and cloth on day 2.

By contrast, SARS-CoV-2 was more stable on smooth surfaces. No infectious virus could be detected from treated smooth surfaces on day 4 (glass and banknote) or day 7 (stainless steel and plastic).

Strikingly, a detectable level of infectious virus could still be present on the outer layer of a surgical mask on day 7 (∼0·1% of the original inoculum).

Interestingly, a biphasic decay of infectious SARS-CoV-2 could be found in samples recovered from these smooth surfaces. 39 representative non-infectious samples tested positive by RT-PCR(data not shown), showing that non-infectious viruses could still be recovered by the eluents.

We also tested the virucidal effects of disinfectants by adding 15 μL of SARS-CoV-2 culture (∼7·8 log unit of TCID50 per mL) to 135 μL of various disinfectants at working concentration.

With the exception of a 5-min incubation with hand soap, no infectious virus could be detected after a 5-min incubation at room temperature (22°C). Additionally, we also found that SARS-CoV-2 is extremely stable in a wide range of pH values at room temperature (pH 3–10).

Overall, SARS-CoV-2 can be highly stable in a favourable nvironment,
but it is also susceptible to standard disinfection methods.

This work was supported by National Institute of Allergy and Infectious Diseases, National Institutes of Health (contract HHSN272201400006C). LLMP was supported by the Croucher Foundation. We declare no competing interests.